I always give people the option of sitting in their cars during the test most don't want to thou a few want to watch which is fine, so as you all know you as the presenter of the vehicle can act as the assistant to the tester, all you have to do is advise the tester that you will carry out all the procedures that req someone to sit in the car this is perfectly acceptable with vosa, you will have to get out of the car for the tester to get in and inspect all the relavant items when he is done you get back in and follow his instructions, unless its an atl he will use another member of staff to help with suspension checks.
The mot tester is not req to actually drive the car at all unless he/she feels a short road test may be req to verify a fault or to carry out a decelerometer brake test and even then you can go with them as a passenger.
HGV mot's the tester never drives the vehicle its down to the presenter to drive and assist with a few instructions.
So if you are comfortable enough getting your car in and out of the bay and on the brake rollers do it yourself if the garage says you are not insured of its company policy they are talking shit every mot bay in the country is licenced by vosa and every single one has the same set of rules on how the bay works no matter if its a ferrari dealership the presenter has the right to assist with the test period.
I know alot of fellow testers and most are very good and respectfull of other peoples cars however there are a few retards that manage to some how become testers normally found in big fast fit chains.